You cannot add "WD Purple 1TB Surveillance Hard Drive - 5400 RPM Class, SATA 6 Gb/s, 64 MB Cache, 3.5" - WD10PURZ" to the cart because the product is out of stock. WD Purple 6TB Surveillance Hard Disk Drive 5400 RPM Class SATA 6 Gb/s 64MB Cache 3.5 Inch – WD62PURZ Engineered specifically for surveillance security systems,Reduced video frame loss Tuned for write-intensive, low bit-rate, high stream-count applications typical to most surveillance applications Prioritized write-operations for maximized surveillance performance, TLER & ATA streaming support. Package includes a hard drive only – no screws, cables, manuals included. Please purchase mounting hardware and cables separately if necessary. Ships in WD-certified box for safe transit during shipping “Hard Drive Speed: 5400 RPMCache Buffer: 64MB Includes: Quick install guide and Operating System Compatibility: Windows 8, Windows 7, Mac” Built for always-on surveillance storage applications All Frame technology for reduced pixilation and video interruption Designed to support up to 32 HD cameras Caching algorithms specifically designed for security surveillance operation 6 TB capacity holds up to 1,200,000 digital photos, 1,500,000 MP3 files, and 450 hours of HD video. SKU: HDD-DES-WD-6TB/P